16S Active Balancer just "exploded"?

[Metero]

I am not sure but one comment there says it is not a conductive paste. Only an alu oxidation blocker.

hmmm... I watched a youtube video of a professional and he said, you could use this paste for LiFePo4 projects . So to be sure, I will order an other paste. Any suggestions? Dumb question: could you also use the same pastes like when installing a CPU to the socket?

 

[mrzed001]

hmmm... I watched a youtube video of a professional and he said, you could use this paste for LiFePo4 projects . So to be sure, I will order an other paste. Any suggestions? Dumb question: could you also use the same pastes like when installing a CPU to the socket?

If you use a lot of non conductive grease ... then yes that is non conductive.
And you did a stress test and needed a lot of power.

Current takes the path of least resistance (mostly)
The lowest resistance path current could find is through the screw and to the washer.
Bad, very bad. The screw should never be part of the circuit.
The terminal plate, the busbar plate (, the lug plate for BMS) has to be the path of the current.

Can use something like this:

846 - Carbon Conductive Grease

Resistivity of 63 Ω·cm Improves electrical connections between irregular, pitted or corroded surfaces Ensures electrical contact between loose or vibrating parts – best electrical switch lubricant Prevents arcing, pitting, hotspots and welds Reduces mechanical wear Inhibits corrosion Broad...

www.mgchemicals.com

Thermal paste (like for CPU) can be conductive, but not enough. Do not use that

 

[Metero]

If you use a lot of non conductive grease ... then yes that is non conductive.
And you did a stress test and needed a lot of power.

Current takes the path of least resistance (mostly)
The lowest resistance path current could find is through the screw and to the washer.
Bad, very bad. The screw should never be part of the circuit.
The terminal plate, the busbar plate (, the lug plate for BMS) has to be the path of the current.

Can use something like this:

846 - Carbon Conductive Grease

Resistivity of 63 Ω·cm Improves electrical connections between irregular, pitted or corroded surfaces Ensures electrical contact between loose or vibrating parts – best electrical switch lubricant Prevents arcing, pitting, hotspots and welds Reduces mechanical wear Inhibits corrosion Broad...

www.mgchemicals.com

Thermal paste (like for CPU) can be conductive, but not enough. Do not use that

Alright, directly ordered this paste - even its quite pricy with ~23 EUR for 80ml :D - so when it arrives I will clean everything and use this one for the connections. Thanks so far!

Do you think the missing conductivity could've cause any damage? For the cell as well as for the balancer? I am still very worried about the BMS which did not cut off even when the voltage difference went over 0.5V.

 

[upnorthandpersonal]

Alright, directly ordered this paste - even its quite pricy with ~23 EUR for 80ml :D - so when it arrives I will clean everything and use this one for the connections. Thanks so far!

I second that MG Chemicals 847. I've been using it on mine without issues - just make sure you use a thin layer.
The way I clean my terminals is to use something like steel wool that doesn't leave residue and add some oil. The oil prevents oxygen to get into contact with the terminals (and thus prevents the oxide layer from forming right away). Then wipe the terminal with a slightly oily cloth, and coat the terminals with 847.

 

[mrzed001]

Alright, directly ordered this paste - even its quite pricy with ~23 EUR for 80ml :D - so when it arrives I will clean everything and use this one for the connections. Thanks so far!

You know there are no wonders ... usually what is better costs more

Do you think the missing conductivity could've cause any damage? For the cell as well as for the balancer? I am still very worried about the BMS which did not cut off even when the voltage difference went over 0.5V.

Daly BMS ? Lately I read here a lot of problems with Daly. Usually they get a new one.
You can test it.
- Disconnect main + and -
- Cut (disconnect) the last cell out of the pack
- put something there with lower V (put it serial to the cells, add the BMS cable)
- ? maybe you can use a Lab bench power supply to imitate that cell
- and see what BMS does

I do not know if there is any damage.
It is like you had a small arch.
Luckily you stopped that before it could heat up the terminal and the cell.

Also using a BMS and an Active Balancer ... I read a lot of cases when somehow that caused problem.
Not really sure why ... ?

I bought the Active BMS, so there is no such a problem.

 

[Metero]

You know there are no wonders ... usually what is better costs more



Daly BMS ? Lately I read here a lot of problems with Daly. Usually they get a new one.
You can test it.
- Disconnect main + and -
- Cut (disconnect) the last cell out of the pack
- put something there with lower V (put it serial to the cells, add the BMS cable)
- ? maybe you can use a Lab bench power supply to imitate that cell
- and see what BMS does

I do not know if there is any damage.
It is like you had a small arch.
Luckily you stopped that before it could heat up the terminal and the cell.

Also using a BMS and an Active Balancer ... I read a lot of cases when somehow that caused problem.
Not really sure why ... ?

I bought the Active BMS, so there is no such a problem.

Yes, its a 200A 16s Daly BMS with "active balancing" ... but the balancing current is 50mA :D, so not really noticing.

Thanks for the idea. I will probably try this, but I have no lab power supply :/ - will try something else.

Which "Active BMS" do you mean? When I selected all components of the battery pack, I really thought 170 EUR would be enough for a good BMS and I also read a lot of good reviews about Daly.

 

[Steve_S]

Thermal Pastes (heatsink paste for CPU's) is NOT to be used, it's not electrically conductive.
Aluminium Paste has its place but NOT with batteries like this.
These two products below are highly recommended.
* Application Tips:
- Do not put on Threads of screws/bolts as this acts like a Grease and will affect torque readings.
- Use only a very minimal amount between cell terminal face & busbar. Just a light wipe on both contact faces is all that is needed.

No-Alox https://www.idealind.com/ca/en/shop/noalox.html or
OxGuard

Ox-Gard Anti-Oxidant Compound

Ox-Gard Anti-Oxidant Compound contains prime grade zinc and is formulated with metallic zinc to create a compound that enhances electrical and thermal conductivity which is used on high power crimp connections and stud bolt mountings. When the connection is tightened, the grease is displaced...

www.gardnerbender.com

BTW: I use Active Balancers on all of my packs.

<--- QNBBM 8S Active Balancer. (All production packs)
I route the BMS Harness Wires to the Common Block on the QNBBM Balancers then 14Ga wire to Cell Terminal.
*NB: Production Packs use Chargery BMS8T-300's with 300A DCC's.
** Passive Balancing ON only during Charge over 3.300V and to 30mv differential.
this helps prevent runners and assists Active Balancer when at the top of charge cycle.



Hope it helps, Good Luck.
Steve_S





<---- Molex 9-Port for 8S BMS/Balance leads,
With the HelTec Active Balancers (Utility packs) I'm doing similar but BMS Harness & Balancer goto a 9-Port Molex Connector and then to Cells with 14Ga wire.
*NB, Utility Packs also use JBD Smart BMS' PN: JBD-SP08S004

 

[mrzed001]

Yes, its a 200A 16s Daly BMS with "active balancing" ... but the balancing current is 50mA :D, so not really noticing.

I think all Daly have passive balancing. Burn power, not transfer.

Thanks for the idea. I will probably try this, but I have no lab power supply :/ - will try something else.

Which "Active BMS" do you mean? When I selected all components of the battery pack, I really thought 170 EUR would be enough for a good BMS and I also read a lot of good reviews about Daly.

I bought the JK Heltec 200A Active 2A balancing BMS.
https://cncdheltec.en.alibaba.com/p...ve_equalizer_BMS_with_mobile_app_monitor.html

 

[Metero]

Thermal Pastes (heatsink paste for CPU's) is NOT to be used, it's not electrically conductive.
Aluminium Paste has its place but NOT with batteries like this.
These two products below are highly recommended.
* Application Tips:
- Do not put on Threads of screws/bolts as this acts like a Grease and will affect torque readings.
- Use only a very minimal amount between cell terminal face & busbar. Just a light wipe on both contact faces is all that is needed.

No-Alox https://www.idealind.com/ca/en/shop/noalox.html or
OxGuard

Ox-Gard Anti-Oxidant Compound

Ox-Gard Anti-Oxidant Compound contains prime grade zinc and is formulated with metallic zinc to create a compound that enhances electrical and thermal conductivity which is used on high power crimp connections and stud bolt mountings. When the connection is tightened, the grease is displaced...

www.gardnerbender.com

BTW: I use Active Balancers on all of my packs.

<--- QNBBM 8S Active Balancer. (All production packs)
I route the BMS Harness Wires to the Common Block on the QNBBM Balancers then 14Ga wire to Cell Terminal.
*NB: Production Packs use Chargery BMS8T-300's with 300A DCC's.
** Passive Balancing ON only during Charge over 3.300V and to 30mv differential.
this helps prevent runners and assists Active Balancer when at the top of charge cycle.



Hope it helps, Good Luck.
Steve_S



View attachment 60624

<---- Molex 9-Port for 8S BMS/Balance leads,
With the HelTec Active Balancers (Utility packs) I'm doing similar but BMS Harness & Balancer goto a 9-Port Molex Connector and then to Cells with 14Ga wire.
*NB, Utility Packs also use JBD Smart BMS' PN: JBD-SP08S004

When I got this right the QNBBM 8S balancer costs about 170 EUR :D... thats a bit much for an balancer isn't it? And you're also using a passive balancer as well? Why both?

The idea of using molex ports is really interesting as it would save the double wiring at the cell terminals and so reduce the cables inside the battery box. But are there any other positive effects to connect the BMS harness directly to the balancer?

 

[mrzed001]

No-Alox https://www.idealind.com/ca/en/shop/noalox.html or
OxGuard

Ox-Gard Anti-Oxidant Compound

Ox-Gard Anti-Oxidant Compound contains prime grade zinc and is formulated with metallic zinc to create a compound that enhances electrical and thermal conductivity which is used on high power crimp connections and stud bolt mountings. When the connection is tightened, the grease is displaced...

www.gardnerbender.com

Do you have Ohm cm resistance data for any of them ?

 

[Steve_S]

QNBBM's are certainly more costly but also a very different animal and they do work like a charm
The Passive Balancing is built into the Chargery BMS T Series. Active Balancing will be available in the "Chargery B Series".
I use PASSIVE only on the Charge Cycle to knock the top edge off of Runner cells which helps the Active Balancers level up the cells in the packs. I run multiple packs in my Production Bank.

There really should only be one "BMS Lead" to each cell. Most commercial packs also do not connect the Lead to a "post" but rather have a separate "Mid-busbar" screw terminal or soldered connector.

Some people are using these Hella type blocks with Fuses (fused to Max Amps of Active Balancer) so they can fuse each cell. I don't honestly know if the low amp ATC type fuses would be useful but some folks believe it will.

 

[Scph9002]

An active cell balancer will ironically unbalance cells if used when discharging at high C rates. The balancer only can only measure voltage ontop of the busbar where it is connected. Different internal resistances of cells and different resistance on bus bar connection will manifest great voltage difference at high loads when battery is close to full when discharging. Identical amount of energy is leaving each cell when discharging (some in form of heat from bad connections and bad internal resistances) so the cells cant get unbalanced. Only when charging the cells can become unbalanced because some energy is not getting stored in cells but is lost as heat.(anyone disagree?) the balancer reads different voltages still due to different resistances and let current flow from high resistance cells/bussbars to lower resistance cells/bus bars making the cells unbalanced.

ideally the sense leads should be connected at the very start of the positive and negative poles of the cells but that is inside the battery at the very end of the long copper sheet
Or only be put to work when no current is flowing in or out of the battery

Some of your cells and/or hopefully only bus bar connection are very bad.

 

[coolbz]

Active cell balancer is like a micro-managing style boss. Too much of interventions on battery operation do more harm than help.

 

[mrzed001]

@Will Prowse possible the same happened to your active balancer in your latest video ?

And OP used a good quality Heltec active balancer.
This is not the first I read where BMS used together with active balancer ... somehow made a mess.
And I do not understand how or why ? And it bothers me.

 

[DerpsyDoodler]

Hello my friends,
quite new to DIY battery packs but I would say, that I am really sure what I am doing from an electrical perspective - until now .

I finished my first project with building a ~10KWh 16S 48V LiFePo4 battery for my 5KW hybid inverter which is connected to 10 of 310W mono-solarpanels. So far so good. System was running quite well with the LiFePo4 pack for several weeks until I noticed that the cells getting quite unbalanced when going from ~80% to 100% SOC - even I initially top-balanced them at the beginning. So I just ordered an 16S active balancer from AliExpress (Heltec: https://www.aliexpress.com/item/4000938109615.html?spm=a2g0s.9042311.0.0.701c4c4dGOoFQ9) with a maximum balance current of 5A - which seemed really nice and useful to me.
When it arrived a week ago I instantly installed this little PCB with its wires as explained in the manual (https://diysolarforum.com/resources/heltec-capacitive-active-equalization-active-balancer.204/). So connecting the first B- wire to the same battery pole as the BMS (Daly BMS 16S 200A) and then connecting each positive pole in the correct order. Before connecting the balancer I measured each connector/cable to ensure the correct connection order - everything fine, same procedure as connecting the BMS.
Now after 3 days of working really well and without any issues, I decided to make a stress test of the whole system with the battery at 100% SOC. I started with 1KW consumption (~20A) up to 4KW (~83A). When I plugged in the last device with 2.2 KW consumption the BMS did cut off the whole pack. While this happened I noticed the BMS showing one cell with >4V for around 2 seconds. So... I tried the same test again. But now (also the BMS did cut off the battery) the balancer short-circuted with a little spark and a few seconds later (when the battery pack was definitly cutted of) 3 capacitors of the PCB just "popped" / exploded off. That was really a shocking moment and I thought "alright, thats it, everything will be broken now". After I securely disconnected the balancer, I checked every cell and the BMS and everthing seems alright for now - exept the balancer, which is completely destroyed.

NOW the final questions: how the f*ck could this happen? Was it my fault or was the balancer faulty since the beginning? I was hitting 80A to 90A consumption, was it too much for the balancer? What is the maximum consumption you can draw with an active balancer?

Thank you all in advance for your expertise on this topic!

Best regards
Paul

If your cells aren't staying balanced after they've been top balanced, then there's either a problem with the cells or a problem with the wiring/crimps/busbars (high resistance connection(s) somewhere).

Did you sand the terminals and clean with isopropyl before assembly? Did you use noalox or some other ani-corrosion compound?

Did you capacity test the cells independently when you received them?

First thing's first, look for hotspots (indicating a high resistance connection), remediate by disassembly, cleaning (as described above) and reassembly.

You can more easily identify hotspots with a thermal imaging camera. Klein makes some (among others). The one I got was ~300 dollars. you can find some cheapy phone plugin attachments but I have no experience with or knowledge of how well those do or don't work. ymmv.

 

[Steve_S]

2 POINTS:
He was using 2x 8S BMS', if one kicked off (hi likelyhood) the single surge would have Popped the Capacitor.
This evaluation = krap. He needs to top balance the cells & use a proper 16S BMS and not two 8S units.

BTW: This is FINE ELECTRONICS ! How many people use Anti-Static Precautions ? Would you tear apart your PC / Laptop and not protect against Static ? or risk a grand+ worth of electronics ? The easiest way to harm electronics = Static Electricity ! Has always bern true and will always be so.

 

[Crisp]

Hello my friends,
quite new to DIY battery packs but I would say, that I am really sure what I am doing from an electrical perspective - until now .

I finished my first project with building a ~10KWh 16S 48V LiFePo4 battery for my 5KW hybid inverter which is connected to 10 of 310W mono-solarpanels. So far so good. System was running quite well with the LiFePo4 pack for several weeks until I noticed that the cells getting quite unbalanced when going from ~80% to 100% SOC - even I initially top-balanced them at the beginning. So I just ordered an 16S active balancer from AliExpress (Heltec: https://www.aliexpress.com/item/4000938109615.html?spm=a2g0s.9042311.0.0.701c4c4dGOoFQ9) with a maximum balance current of 5A - which seemed really nice and useful to me.
When it arrived a week ago I instantly installed this little PCB with its wires as explained in the manual (https://diysolarforum.com/resources/heltec-capacitive-active-equalization-active-balancer.204/). So connecting the first B- wire to the same battery pole as the BMS (Daly BMS 16S 200A) and then connecting each positive pole in the correct order. Before connecting the balancer I measured each connector/cable to ensure the correct connection order - everything fine, same procedure as connecting the BMS.
Now after 3 days of working really well and without any issues, I decided to make a stress test of the whole system with the battery at 100% SOC. I started with 1KW consumption (~20A) up to 4KW (~83A). When I plugged in the last device with 2.2 KW consumption the BMS did cut off the whole pack. While this happened I noticed the BMS showing one cell with >4V for around 2 seconds. So... I tried the same test again. But now (also the BMS did cut off the battery) the balancer short-circuted with a little spark and a few seconds later (when the battery pack was definitly cutted of) 3 capacitors of the PCB just "popped" / exploded off. That was really a shocking moment and I thought "alright, thats it, everything will be broken now". After I securely disconnected the balancer, I checked every cell and the BMS and everthing seems alright for now - exept the balancer, which is completely destroyed.

NOW the final questions: how the f*ck could this happen? Was it my fault or was the balancer faulty since the beginning? I was hitting 80A to 90A consumption, was it too much for the balancer? What is the maximum consumption you can draw with an active balancer?

Thank you all in advance for your expertise on this topic!

Best regards
Paul

Just toasted 2 Heltec 16s balancers myself. Called heltec tech @ Amazon and they offered replacements so fast it made me suspect a known problem. (Yes, i Tripple checked and metered the connector, twice...). Haven't hooked up the replacements yet.

 

[Steve_S]

People mess up the wires all the time & fry them.
Sheesh, some just have to take a leap eh... gee wiz people... it's so damned tedious and soooo tired already.

 

[Just John]

Dumb question: could you also use the same pastes like when installing a CPU to the socket?

No.

 

[Just John]

Do you have Ohm cm resistance data for any of them ?

Both have been used by electricians to prevent corrosion for about 40+ years.
They are dirt cheap, and effective. They certainly meet code inspections in south Florida.